The demands on a Division I volleyball player might be greater than for any college athlete. The regular season for the 2013 Gophers calls from 33 matches from the end of August to the end of November, followed by what has become annual participation in the NCAA’s 64-team tournament.

There is also a spring schedule in volleyball. There are grinding, offseason workouts, and there are in-season practices that can last for three hours. Full bore. Vaulting, hitting, blocking, setting, diving, digging.

Tori Dixon took the usual route to being recruited to big-time college volleyball: displaying her talent with a club team (Northern Lights).

The best guess on Dixon’s part is that it was in the spring of 2008, playing for her club team, that she started to pay attention to episodes of her heart rate “racing out of control.”

Dixon’s response was to make a joke about it to teammates, and to blame it on fatigue and/or dehydration.

“I would think, ‘I must not have slept well last night,’ or ‘I have to drink more water,’ ” Dixon said. “I always had a few episodes of a rapid heartbeat, but what changed was the frequency: from maybe once a month, to once a week, to a few times a week, to multiple times a day.

Tori Dixon’s dominance at middle blocker is a big reason the Gophers are 21-4 and No. 10 in the coaches’ national rankings.

“I finally said, ‘This can’t be normal.’ ”

Dixon had made it through three sterling years as a middle blocker for the Gophers. She had received an invitation from USA Volleyball to attend the national team camp in Colorado Springs in July 2013.

That made her one of three collegians among the two dozen candidates invited to coach Karch Kiraly’s camp.

Hugh McCutcheon was Kiraly’s predecessor as national coach. He’s now in his second season as the Gophers coach. He was among those curious in February workouts as to why the 6-3 Dixon wasn’t having her usual finish at the front of team sprints.

“Nobody said it directly, but I think the coaches were wondering if I was slacking off,” Dixon said.

That never would be the case with a competitor such as Dixon. It was fatigue. It was her racing heart. It was atrioventricular nodal reentrant tachycardia.

A reporter said to Dixon this week: “If you can spell it, they hand you a diploma.”

Tori smiled and said: “In that case, I’m not getting one.”

(Note: Actually, she is, in December after 3½ years, in sports management).

One workout day last February, Dixon went to team trainer Ronni Beatty-Kollasch and was crying.

“I’ve never seen that,” Beatty-Kollasch said. “Tori’s not the type to cry about anything. But she told me about her heart pounding, her fatigue.

“We’re fortunate to be at this university, with our great hospital and great doctors. It didn’t take long for them to figure it out.”

Dixon had an extra node in her heart. And this little bugger would fire up in a cry for attention, and that would get the whole blood-pumping plant rolling, and Tori’s heart would start pounding at its ridiculously high number.

“It wasn’t life threatening,” Dixon said. “But if I wanted to keep playing volleyball, the doctors said I needed the surgery to have the node removed.”

Beatty-Kollasch said: “In Tori’s case, the extra node was right next to some of the real important stuff with the heart, so the surgery was very intricate.”

The heart surgery took place on March 25. Dr. Scott Sakaguchi was the main man. The original hope was for a three-hour procedure in which the node could be frozen away.

“It was squeezed in there too tight, I guess,” Tori said. “They had to fry it off.”

Fried in minute pieces. The surgery took seven hours.

“I was outside waiting, going crazy,” Beatty-Kollasch said.

Pam Dixon, Tori’s mother, also was going crazy … except she was in the Carribbean, on a cruise with Tori’s father, David, and her two younger siblings.

The Dixons had paid in full for the family cruise months before Tori’s situation was diagnosed. Tori and everyone else involved told the Dixons to take the cruise for two reasons:

One, Tori was going to be fine and, two, there’s nothing they could do to help.

“Pam was calling every time she got a cell signal,” Beatty-Kollasch said. “It would last about three seconds and the call would be dropped.”

Seven hours after Dr. Sakaguchi started, the node was gone and Tori was started on a quick recovery.

“I haven’t had an episode since the surgery,” Dixon said. “I feel great.”

She is having a magnificent senior season in the middle of Big Ten competition that is challenging throughout a double round-robin and two matches a weekend.

Dixon was a second-team All-America and a unanimous All-Big Ten first team pick in 2012. She could move up the remaining notch in the All-America rankings this time.

The Gophers are 21-4 overall, 9-3 in the Big Ten and rated No. 10 nationally. They have a four-match homestand that includes the two teams ahead of them in the conference: No. 8 Nebraska (10-2) on Sunday afternoon, and No. 2 Penn State (11-1) on Nov. 16.

Minnesota is 8-0 at home this season. And the crowds in the Sports Pavilion for those matches might be such that David Dixon, once an NFL offensive lineman, won’t have his usual isolated space to watch and cheer for his daughter.

Speaking of which, Tori: That no-crying deal … surely, you cried in January 1999, when one Anderson missed a field goal, and another Andersen made a field goal, and your Dad and the Vikings didn’t go to the Super Bowl?

“No … I was 6 years old,” Dixon said. “All I remember is that I didn’t get to go to the game.”

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